JPH08241904A - Method for connecting lead wire of electronic device - Google Patents

Abstract

PURPOSE: To provide a method for connecting the lead wire of an electronic device for protecting the surface of a smoothed metal plate. CONSTITUTION: An insulation substrate 14 with a bonding pad 16 and an electrical circuit is sealed to the surface of a metal case 10 at a side with a recessed part 10a. Then, one edge 18a of a lead small-gauge wire 18 consisting of, for example, aluminum is connected to a surface 16a of the bonding pad 16 mounted on the reverse-rubber side surface of the insulation substrate 14 and further the other edge 18b of the lead small-gauge wire 18 is connected to a surface 10b at the bottom of the recessed part 10a. The lead small-gauge wire 18 is connected by the wire bonding method, thus preventing the surface 10b at the bottom of the recessed part 10a where the lead small-gauge wire 18 is connected from being damaged externally.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead wire connecting method for an electronic device.

[0002]

2. Description of the Related Art Conventionally, as a method for connecting a lead wire of an electronic device, there is a lead wire connecting method for an electronic device disclosed in Japanese Patent Application Laid-Open No. 4-337641. This electronic device lead wire connection method is such that when a heat sink made of aluminum for housing the electronic device is formed by forging, a cylindrical pedestal is formed at the same time, and the surface of the pedestal is cut, ground or polished to a predetermined shape. Smooth the surface roughness of. Then, lead thin wires are connected to the smoothed surface of the pedestal portion by wire bonding.

[0003]

However, according to the lead wire connecting method for an electronic device disclosed in Japanese Patent Application Laid-Open No. 4-337641, the pedestal portion is formed in a convex shape with respect to the surrounding surface. The surface of the pedestal part will protrude from the surface around it. However, this pedestal part is smoothed to a predetermined surface roughness for connecting the lead thin wires. Therefore, if the surface of the pedestal is damaged when the heat sink is transported, the scratches on the surface of the pedestal hinder the good connection of the thin lead wires.

It is an object of the present invention to provide a lead wire connecting method for an electronic device, which protects the surface of the recess of the metal plate. In addition, another object of the present invention is to provide a lead wire connecting method for an electronic device which is less likely to be damaged from the outside.

[0005]

According to a first aspect of the present invention, there is provided a method for connecting a lead wire of an electronic device according to the present invention, wherein a step of forming a metal plate having a concave portion by forging, and the concave portion. And connecting a thin lead wire to the surface of the. Further, claim 2 according to the present invention
The lead wire connecting method for an electronic device according to the first aspect is characterized in that, in the lead wire connecting method for an electronic device according to the first aspect, the concave portion is located above a convex portion formed on the metal plate.

Further, the lead wire connecting method for an electronic device according to a third aspect of the present invention is the method for connecting a lead wire for an electronic device according to the first or second aspect, in which a metal plate having a recess is formed by forging. And a step of smoothing the surface of the recess, and a step of connecting a lead thin wire to the surface of the recess.

Furthermore, a lead wire connecting method for an electronic device according to a fourth aspect of the present invention is the method according to the first, second or third aspect.
In the electronic device lead wire connecting method described above, the recess has a side wall that widens from the bottom side toward the opening end side. The lead wire connecting method for an electronic device according to a fifth aspect of the present invention is the lead wire connecting method for an electronic device according to the second aspect, wherein the concave portion is a long groove formed on an upper surface of the convex portion. Is characterized by.

[0008]

According to the lead wire connecting method of the electronic device of the present invention, the surface of the recess formed in the metal plate is used as the connecting surface of the lead thin wire. The connection surface is protected by the surface of the metal plate surrounding the periphery of the. That is, the surface of the recess, which is the connection surface, does not protrude from the outer peripheral edge of the recess. As a result, there is an effect of preventing damage to the surface connecting the lead wires when carrying a metal plate having a recess formed therein. Therefore, the surface of the recess of the metal plate is protected and the surface of the recess is less likely to be damaged from the outside. further,
To prevent damage to the surface connecting the lead wires,
Fine lead wires can be satisfactorily connected to the surface of the recess, and the yield of lead fine wire connection can be improved. Furthermore, there is an effect that sufficient connection strength can be obtained between the lead thin wire after connection and the connecting surface of the lead thin wire.

According to the lead wire connecting method for an electronic device of the third aspect of the present invention, the step of forming a metal plate having a recess by forging and the step of connecting a lead wire to the surface of the recess. Since the step of processing the surface of the recess to be smooth is included, it is easy to connect the lead thin wire to the surface of the recess. As a result, there is an effect that sufficient connection strength can be obtained between the lead thin wire after connection and the connecting surface of the lead thin wire.

Further, according to the lead wire connecting method of the electronic device of the fourth aspect of the present invention, since the recess has the side wall that widens from the bottom side toward the opening end side, the lead connecting to the surface of the recess is formed. It is not necessary to draw the thin wire perpendicular to the surface, and it can be drawn obliquely according to the inclination of the side wall. This has the effect of improving the degree of freedom in routing the lead thin wires. Moreover, since the side wall of the recess is widened, the opening area is larger than the surface area of the connection surface of the recess. Therefore, there is an effect that the positioning of the connecting jig or the like at the time of connecting the thin lead wires becomes easy.

Furthermore, according to the lead wire connecting method of the electronic device of the fifth aspect of the present invention, since the concave portion located above the convex portion is a long groove formed on the upper surface of the convex portion, The thin lead wire connected to the surface does not have to be drawn out perpendicularly to the surface, and can be drawn out from the side wall direction of the convex portion. As a result, the degree of freedom in routing the thin lead wire is improved, and the length of the thin lead wire can be minimized.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIGS. 1 to 3 show a first embodiment in which the lead wire connecting method for an electronic device of the present invention is applied to a case ground wiring connection of an electric circuit.

As shown in FIG. 2, a metal case 10 made of aluminum, an aluminum alloy, or copper having a recess 10a on one side is formed by pressing or cold forging. The space formed inside the recess 10a is, for example, a column having a diameter of 4.0 to 4.5 mm, and the recess 10a is formed so that the depth thereof is 3.5 mm or less. The surface 10b at the bottom of the recess 10a is a region to which a lead wire 18 to be described later is connected (hereinafter referred to as "wire bonding region"), and thus the surface roughness is finished to 10 μm or less by cutting, grinding or polishing. Is desirable, and the thickness of the bottom is set to 10 mm or more.

As shown in FIG. 1, the bonding pad 16 is formed on the surface of the metal case 10 on the side having the recess 10a.
The insulating substrate 14 on which an electric circuit (not shown) is mounted is fixed by the rubber 12. After this, the insulating substrate 14
One end 18a of a lead thin wire 18 made of, for example, aluminum is connected to the surface 16a of the bonding pad 16 mounted on the side of the rubber opposite to the lead thin wire 18
The other end 18b is connected to the wire bonding region of the recess 10a. The lead thin wire 18 is connected by a wire bonding method.

Through the above steps, the bonding pad 16 on the insulating substrate 14 is electrically connected to the metal case 10. Here, a modified example 1 of the first embodiment is shown in FIG.
In the first modification, the inner peripheral wall 10c of the recess 10a is replaced by the surface 1 of the bottom.
This is an example in which the inner peripheral wall 10c is tapered not by making it perpendicular to 0b but by giving an angle in a predetermined range.

As shown in FIG. 3, the angle θ of the inner peripheral wall 10c with respect to the surface 10b is set in the range of 10 ° <θ <50 °, and the angle from the surface 10b at the bottom of the recess 10a to the opening surface of the recess 10a is increased. It is expanding toward you. As a result, the lead thin wire 18 connected to the surface 10b can be pulled out in an oblique direction in accordance with the inclination of the side wall 10c, which has the effect of improving the degree of freedom in routing the lead thin wire 18. Further, since the opening area of the recess 10a is larger than the area of the bottom surface 10b, there is an effect that alignment of a connecting jig or the like when connecting the lead thin wires 18 becomes easy.

According to the first embodiment, since the bottom surface 10b of the recess 10a formed in the metal case 10 is used as the wire bonding area, the wire bonding area is formed on the surface of the metal case 10 surrounding the wire bonding area. Is protected. This has an effect of preventing damage to the wire bonding region when the metal plate 10 having the recess 10a formed therein is transported or the like. Therefore, the fine lead wires 18 can be satisfactorily connected to the surface 10b, which is the wire bonding region, without requiring surface treatment of the wire bonding region by slight cutting, grinding or polishing, and the yield of wire bonding connection is improved. is there. Further, the thin lead wire 18 and the surface 10b after connection
There is an effect that a sufficient connection strength can be obtained between and.

(Second Embodiment) FIG. 4 to FIG. 11 show a second embodiment in which the lead wire connecting method of the electronic device of the present invention is applied to the case ground wiring connection of an electric circuit. The same reference numerals are attached to the substantially same components as those in the first embodiment. The second embodiment is an example in which the concave portion 10a is formed above the convex portion 20.

As shown in FIGS. 4 to 6, the metal case 10 is used.
A columnar convex portion 20 is formed on one side of, and a concave portion 10a is formed on the upper portion of the convex portion 20. The convex portion 20 and the concave portion 10a are integrally formed when the metal case 10 is formed by pressing or cold forging. 5 and 6 are a plan view and a cross-sectional view of the metal case 10 before the lead wires 18 are connected by wire bonding, and a recess 21a similar to the recess 10a described in the first embodiment is provided above the projection 20. It can be seen that is formed.

On the other hand, according to the conventional comparative example shown in FIG. 12, one end 28a of the lead wire 28 connected to the convex portion 40 formed on the metal case 20 is connected to the surface 26a of the bonding pad 26 of the insulating substrate 24. And the other end 28b
Are connected to the upper surface 40 a of the convex portion 40. The upper surface 40a of the convex portion 40 is a wire bonding region smoothed to a predetermined surface roughness that enables good bonding connection. However, since the upper surface 40a is located on the top of the convex portion 40, the metal case 20 located around the upper surface 40a.
It is protruding compared to the surface of. That is, the upper surface 40a, which is the wire bonding region, projects from the peripheral surface. Therefore, when carrying the metal case 20, the upper surface 40a smoothed to a predetermined surface roughness is used.
Has the drawback of being easily damaged.

In contrast to this comparative example, according to the second embodiment,
The thin lead wire 1 is attached to the protrusion 20 protruding from the surrounding surface.
Even when 8 is connected by wire bonding, since the bottom surface 21b of the concave portion 21a, which is the wire bonding region, is located at the bottom recessed from the upper surface 20a of the convex portion 20, when the metal case 10 is transported, Does not damage the bonding area.

A modified example 2 of the second embodiment is shown in FIGS. 7 and 8. Modified Example 2 shown in FIGS. 7 and 8 is an example in which the inner peripheral wall 26c of the recess 26a is not perpendicular to the surface 26b of the bottom portion, but the inner peripheral wall 26c is tapered by giving an angle within a predetermined range. That is, this is an example in which the first modification of the first embodiment is applied to the concave portion integrally formed with the convex portion of the second embodiment. As a result, the lead thin wire (not shown) connected to the surface 26b can be pulled out in an oblique direction in accordance with the inclination of the side wall 26c, which has the effect of improving the degree of freedom in routing the lead thin wire. In addition, the recess 2
Since the opening area of 6a is larger, the effect of facilitating the alignment of the connecting jig or the like when connecting the lead thin wires is obtained.

Here, a modified example 3 of the second embodiment is shown in FIG.
~ Shown in FIG. Modification 3 shown in FIGS. 9 to 11 is an example in which a concave portion integrally formed with a cylindrical convex portion has a groove shape.
As shown in FIGS. 10 and 11, the groove portion 31a integrally formed with the convex portion is formed so as to penetrate through the opposite side walls of the convex portion, so that the surface 31 of the bottom portion of the groove portion 31a is formed.
b is protected by a set of protrusions 30 having a semi-cylindrical shape with the arc of the protrusion as the contour of the outer wall surface. That is, the surface 31b of the bottom of the groove 31a which is the wire bonding region.
Is located on the bottom recessed from the upper surface 30a of the protrusion 30, so that the wire bonding region is not damaged when the metal case 10 is transported. Also, surface 3
Since the thin lead wire 18 connected to 1b can be pulled out from between the set of protrusions 30, the degree of freedom in routing the thin lead wire 18 is improved, and there is an effect that the thin lead wire 18 can be run in the shortest distance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a metal plate, an insulating substrate and the like connected by a lead wire connecting method for an electronic device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a metal plate used in the lead wire connecting method of the electronic device according to the first embodiment.

FIG. 3 is a cross-sectional view of a metal plate used in a first modification of the lead wire connecting method for the electronic device according to the first embodiment.

FIG. 4 is a perspective view showing a metal plate, an insulating substrate and the like which are connected by a lead wire connecting method for an electronic device according to a second embodiment of the present invention.

FIG. 5 is a plan view of a metal plate used in a lead wire connecting method for an electronic device according to a second embodiment.

6 is a sectional view taken along line VI-VI shown in FIG.

FIG. 7 is a plan view of a metal plate used in a modification 2 of the lead wire connecting method for the electronic device according to the second embodiment.

8 is a sectional view taken along line VIII-VIII shown in FIG.

FIG. 9 is a perspective view showing a metal plate, an insulating substrate, and the like connected by a modification 3 of the lead wire connecting method for the electronic device according to the second embodiment.

FIG. 10 is a plan view of a metal plate used in Modification 3;

11 is a sectional view taken along line XI-XI shown in FIG.

FIG. 12 is a perspective view showing a metal plate, an insulating substrate and the like connected by a lead wire connecting method of an electronic device according to a conventional comparative example.

[Explanation of symbols]

 10 Metal Cases 10a, 21a, 26a Recesses 10b, 21b, 26b, 31b Surfaces (Recess Surfaces) 10c, 31c Inner Walls (Side Walls) 12 Rubber 14 Insulating Substrate 16 Bonding Pads 18 Lead Fine Wires 31a Grooves (Recesses, Long Grooves)

Claims (5)

[Claims] 1. A lead wire connecting method for an electronic device, comprising: a step of forming a metal plate having a concave portion by forging; and a step of connecting a fine lead wire to a surface of the concave portion. 2. The method of connecting a lead wire of an electronic device according to claim 1, wherein the concave portion is located above the convex portion formed on the metal plate. 3. A step of forming a metal plate having a recess by forging, a step of smoothing the surface of the recess, and a step of connecting a lead thin wire to the surface of the recess. The lead wire connecting method for an electronic device according to claim 1. 4. The lead wire connecting method for an electronic device according to claim 1, wherein the recess has a side wall that widens from the bottom side toward the opening end side. 5. The method of connecting a lead wire of an electronic device according to claim 2, wherein the concave portion is a long groove formed on the upper surface of the convex portion.